Packet-based communication systems allow the user of a device, such as a personal computer, to communicate across a computer network such as the Internet. Packet-based communication systems include video over internet protocol (IP) communication systems, which allow users to exchange live video streams over the Internet. These systems are beneficial to the user as they are often of significantly lower cost than fixed line or mobile networks. This may particularly be the case for long-distance communication. To use a video-over-IP system, the user must install and execute client software on their device. The client software provides the video IP connections as well as other functions such as registration and authentication. In addition to video communication, the client may also provide further features such as audio, instant messaging (“IM”), SMS messaging, and voicemail.
One type of packet-based communication system uses a peer-to-peer (“P2P”) topology built on proprietary protocols. To enable access to a peer-to-peer system, the user must execute P2P client software provided by a P2P software provider on their computer, and register with the P2P system. When the user registers with the P2P system the client software is provided with a digital certificate from a server. Once the client software has been provided with the certificate, communication can subsequently be set up and routed between users of the P2P system without the further use of a server. In particular, the users can establish their own communication routes through the P2P system based on the exchange of one or more digital certificates (or user identity certificates, “UIC”), which enable access to the P2P system. The exchange of the digital certificates between users provides proof of the users' identities and that they are suitably authorised and authenticated in the P2P system. Therefore, the presentation of digital certificates provides trust in the identity of the user. It is therefore a characteristic of peer-to-peer communication that the communication is not routed using a server but directly from end-user to end-user. Further details on such a P2P system are disclosed in WO 2005/009019.
Users are thus able to make face-to-face video calls, by exchanging video images taken from a web-cam mounted on each of their respective computer terminals.
However, there is still a problem with such video calls in that the degree of interaction between users is limited. When meeting in person, information is not only communicated by voice, facial expression and gesticulation: some information is also added by the context of a shared experience, situation or surroundings. When communicating remotely via a video call, this context may be lost and so communications may be more cumbersome or confused.